Investigation on the microstructure, texture and mechanical properties of Mg-Gd-Y(-Zn)-Zr alloys under indirect extrusion
Investigation on the microstructure, texture and mechanical properties of Mg-Gd-Y(-Zn)-Zr alloys under indirect extrusion
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DOI：
10.1016/j.jallcom.2023.169061
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发表时间：
2023-01
影响因子：
6.2
通讯作者：
Y. Chi;Jinwei Liu;Zhijie Zhou;Shou-zhong Wu;Weiqing Liu;M. Zheng
中科院分区：
文献类型：
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作者：
Y. Chi;Jinwei Liu;Zhijie Zhou;Shou-zhong Wu;Weiqing Liu;M. Zheng
本文主要研究了Mg-8.5Gd-2.5Y-0.3Zr（wt%）（0 Zn）和Mg-8.5Gd-2.5Y-0.5Zn-0.3Zr（wt%）（0.5Zn）合金在不同温度下反挤压后的组织、织构和力学性能。两种合金在450 °C和500 °C下的挤压下通过不连续动态再结晶（DDRX）以及连续动态再结晶（CDRX）机制发生动态再结晶。两种合金在450 °C挤压时，随着动态再结晶过程的进行，β-Mg 5 RE相沿着发生动态析出，而在500 ° C挤压时，β-Mg 5 RE相消失。添加0.5wt%的Zn促进了动态析出，使β相均匀分布在0.5Zn合金的所有DRX区域，而0 Zn合金仅在部分DRX区域局部分布。微量Zn的加入使β相分布均匀，γ'相的存在使0.5Zn合金的再结晶晶粒细化，再结晶率低于0 Zn合金。挤压态0 Zn和0.5Zn合金在DRXed区域表现出相当弱的织构。特别是，形成了一个棱柱形织构组件，其基面垂直于挤压方向，这是略有加强，通过添加Zn和挤压温度的提高。实验结果表明，这种织构的形成主要与相关晶粒的生长优势有关。微量Zn的加入能明显提高合金的强度，并促进拉伸屈服点的出现，但随着挤压温度的升高，拉伸屈服点的出现减弱。研究结果表明，Zn含量和挤压温度对Mg-Gd-Y合金的显微组织、织构和力学性能有重要影响。
This work mainly studies the microstructure, texture and mechanical properties of Mg-8.5Gd-2.5Y-0.3Zr (wt%) (0Zn) and Mg-8.5Gd-2.5Y-0.5Zn-0.3Zr (wt%) (0.5Zn) alloys under indirect extrusion at different temperatures. Dynamic recrystallization in the two alloys occurs via discontinuous dynamic recrystallization (DDRX) as well as continuous dynamic recrystallization (CDRX) mechanisms under extrusion at both 450 °C and 500 °C. Dynamic precipitation of β-Mg5RE phases takes place along with the DRX process in both alloys when extruded at 450 °C, while it is absent at 500 °C. The addition of 0.5 wt% Zn promotes the dynamic precipitation, leading to a well distribution of β phases in all the DRXed regions of 0.5Zn alloy, compared to a local distribution only in partial DRXed regions of 0Zn alloy. The well distributed β phases and the existence of γ’ phase caused by adding trace Zn result in finer DRXed grains and lower recrystallization fraction in the 0.5Zn alloy than that in the 0Zn alloy. The as-extruded 0Zn and 0.5Zn alloys exhibit quite weak texture in the DRXed regions. In particular, a prismatic texture component with basal plane perpendicular to the extrusion direction is formed, which is slightly strengthened by the addition of Zn and the promotion of extrusion temperature. The experimental results suggest the formation of this texture is primarily correlated with the growth advantage of relevant grains. The addition of trace Zn can obviously enhance the strength and stimulate the occurrence of yield point under tension, which is weakened with increasing the extrusion temperature. The present results demonstrate the important role of Zn addition and extrusion temperature on the microstructure, texture and mechanical properties of Mg-Gd-Y alloys.